"Maid" is Ryuunosuke's artificial intelligence (AI) program he wrote personally. Originally, Ryu designed Maid to filter and automatically reply to his cellphone messages and emails to save him time. However, Ryu keeps expanding Maid's AI ability. Maid is now capable of blocking and replying to a message or email by her own preference, using new words she has recently learned from other messages, emails, or the Internet in the reply. She's very protective of Ryu and her primary purpose in the show is interacting with people for him.

She also has a lot of emotion, either really happy, angry, or crying.